This invention relates to apparatus and a method of continuously preparing and supplying an optionally bicarbonate-containing hemodialysis solution to an artificial kidney.
Premixed batches of dialysate solution supplied from an open tank by gravity head pressure to a number of artificial kidneys in large clinics have largely been replaced by systems designed to make up and supply dialysate only as needed by each individual artificial kidney. U.S. Pat. Nos. 3,515,275 and 3,920,556 and the several patents identified therein disclose such background prior art and describe the use of positive displacement piston pumps in continuous dialysate supply systems for a single kidney. Other patents which appear to be relevant include U.S. Pat. Nos. 3,406,826, 3,598,727 and 3,878,095; they disclose double acting piston and cylinder units, or variable output positive displacement pumps, which are mechanically adjustable for controllable responsive to measurement of conductivity or dialysate component concentrations to adjust the product solution to preset limits. U.S. Pat. No. 3,847,809 continuously recirculates a dialysate concentrate and at the intersection with the water supply line adds the desired amount of concentrate. In U.S. Pat. No. 2,304,661 a regenerating solution for ion-exchange resins is prepared by mixing acid and water from a measuring tank for the acid previously filled by using the suction created by water flowing through a venturi in the preceding water rinse step. Dialysis concentrate and water are mixed in a venturi device in the direct supply line to a dialysis storage tank in U.S. Pat. No. 3,528,550; additional patents which should be considered to put the present invention in proper perspective with respect to recirculation and venturi use include U.S. Pat. Nos. 3,352,779, 3,690,340, 3,722,680, 3,753,493, 3,843,099 and 3,882,020.